Cushion for centrifugal tubes



p 1936- A. E FLOWERS I CUSHION FOR CENTRIFUGAL TUBES Filed July 29, "19312 2 Sheets-Sheet 1 //Vl EA//'0 f y/arr, 5 F/owrs Sept. 1, 1936,

A. E. FLOWERS CUSHION FOR CENTRIFUGAL. TUBES Filed July 29, 1932 2 Sheets-Sheet 2 Patented Sept. 1, 1936 Alan E. Flowers, Poughkeeps'ie, N. Y; assignor to The De Laval Separator Company, New York .N."Y., a corporation of New Jersey Application July 29. 1932. Serial 'No. 626,037 11 Claims. (01. 233-26) In machines for centrifugally separating samples of liquids into their constituents of different specific gravities it has been common practice to place the liquid in a graduated glass tube usually tapered to. a smaller diameter at its lower end and insert this tube into a metal cup more or less closely conforming to the shape of the tube. This cup is, by trunnions on its sides, supported from a rotatinghead on a vertical shaft. When the head is rotated at high speed, each tube. is under a powerful force tending to slide it outward in its cup and if there is excessive pressureat any one spot the tube is apt to be broken.

- A common means to reduce breakage of tubes is to fill the space between the tube and the cup with'a heavy liquid such as salt water or glycerine. It has also been common practice to place around the bottoms of the tubes rubber rings more or less closely approximating the shape of thefspace between, the metal cups and the glass tubes; With high speed centrifuges these expedients have not accomplished the purpose of insuring against breakage.

Ihave found'that a cushion of rubber or other flexible and elastic material of a length approximating that of the taper portion of the glass tube and having numerous longitudinal ribs'on the outside will accommodate itself tothe. space between'the cup and the tube and be thereby better able to support the tube.

Instead of forming the outside of the cushion with longitudinal ribs I may make it with both longitudinal and circumferential grooves leaving between them many projections or I may mold in the outer'por'ti'on many holes that may or may not extend entirely through the wall. If they do extend entirely through, they should preferably, though not necessarily, be much smaller at the inner side than the outer side of the wall.

I have also found that if the inside of the cushion is smooth there is danger that when the glass tube is forced into it and the air squeezed out from between the tube and cushion, this space will be so tightly shut that air cannot enter, making it very difiicult to withdraw the tube. One or more narrow longitudinal grooves in the inside of the cushion will permit the entrance of air and easy removal of the tubes.

In the accompanying drawings, which show preferred embodiments of the invention:

Fig. 1 is a longitudinal section of one type of a cup, a tube and a cushion embodying my invention.

Fig. 2 is a perspective view of the cushion.

Fig. 3 is a longitudinal section of the cushion.

Fig. 4 is a transverse section through 'jthie cushion on the line 4-4 of Fig. 3.

Fig. 5 is a longitudinal section of another shape of glass tube, cushion and metal cup.

Fig. 6 is a transverse section through the cush ion on line 6--B of Fig. 5. v Fig. '7 is a perspective view of a modified form of cushion. I

Fig. 8 is a detail sectional viewof a modification. Referring firstto the construction shown cushion d, .of a length approximating that of the; tapered portions of the tube and cup, the inner wall'of whose" body'corresponds in diameter and taper to the outer wall of the tube, or so nearly corresponds thereto that-the cushion will have close contact therewith in operation. The outer wall of the cushion body varies in diameter from, at its wider end, about the internal diameter of the opposing wall of thecup to, at it'snarrower end, substantially less than the diameter of the narrow end of the cup; The cushion body is provided, along its outer wall, with ribs c, also of flexible and'elastic material and preferably inte'gral with the body, and extending preferably longitudinally, the ribsbeing of a'height at least sufficient, without distortion, to span the space between the cup and the tube and which therefore "taper in height"from'the'narrower endof the cushion toward its wider end. The cushion may also be described as having a wall of a shape and thickness to approximately fill the space between the cup and the tube and preferably in creasing in thickness from the wide toward the narrow end and provided with grooves or flutes 1 extending preferably longitudinally, and of a depth gradually decreasing from the narrow toward the wide end of the cushion and of a width gradually increasing from the narrow toward the wide end of the cushion.

In operation, when centrifugal force tends to drive the tube toward the bottom of the cup the ribs are flattened and by their elasticity provide an approximation to a uniform support over a major portion of the area of the taper part of the glass tube, thus preventing breakage.

In Figs. 5 and 6 is shown a glass tube g which, from its rear end, is tapered throughout the major portion of its length, its front end having .10 in Figs. 1, 2, 3 and 4: The metal cup a adapted to The cushion shown in Fig. 8 isformed with numerous holes, some of which, 111., extendentirely through the wall and some of which-m1, ex-

tend from the outside partly through the walls;

These holes, or at least those which extend en-' tirely through the wall, are of substantially less diameter at the inner side than at the outer side of the wall.

The cup shown in Fig. 5 has in and of itself peculiar advantages regardless of its method of support. Such cup forms the subject-matter of a separate application filed by me November 14, 1932, Serial No. 642,499 now matured into'U. S. Patent No. 2,009,690, dated July 30, 1935.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. A supporting cushion for glass centrifuge tubes, comprising a tapered tubular body of flexible and elastic material, and flexible and elastic ribs extending longitudinally along the outer face of the body, said ribs decreasing in height from the narrower end toward the Wider end of the cushion.

2. A supporting device for glass tubes, comprising a tapered cushion. of flexible and elastic material whose wall increases in thickness from the wide end toward the narrow end of the cushion and is longitudinally fluted in its outer face.

3. A supporting device for, glass centrifuge tubes, comprising a tapered cushion of flexible and elastic material provided with longitudinally extending grooves whose width increases, and whose depth decreases, from the narrower end toward the wider end of the cushion.

4. The combination, with a glass centrifuge tube, of a flexible and elastic cup having an interior shape and size approximating those of the forward portion of the glass tube. and a tapered outer face provided with approximately uniformly distributed flexible and elasticribs.

5. The combination,- with a glass centrifuge. tube, of a flexible and elastic cup having an interior shape and size approximating those of the forward portion of the glass tube, and a tapered outer face provided with substantially uniformly spaced apart flexible and elastic ribs extending longitudinally of the cup.

6. The combination, with a glass centrifuge tube having a tapered forward end, of a flexible and elastic tapered cup having an interior shape and size approximating those of the forward portion of the glass tube, and flexible and elastic ribs extending longitudinally along the tapered mouter face of the cup, said ribs decreasing in height from the narrower end toward the wider end of the cup.

7. The combination, with a glass centrifuge tube having a tapered forward end, of a flexible "andelastic tapered cup having an interior shape and size approximating those of the forward portion of the glass tube, said cup having formed in its outer jface longitudinally extending grooves whose depth decreases from the narrower toward the wider end of the cup.

8. The combination, With a glass centrifuge tube, of a flexible and elastic cup fittable up on the tube and having deformable substantially uniformly distributed projecting members on its outer face and having one or more narrow longitudinal grooves in its inner face.

9. The combination, with a glass centrifuge tube having a frusto-conical forward portion, of a supporting cushion therefor adapted to enclose said forward portion of the glass tube and comprising a flexible and elastic tubular body whose inner and outer surfaces are mainly frustoconical, and approximately uniformly spaced apart flexible and elastic ribs on the outer surface of said body.

10. The combination, with a glass centrifuge tube, of a supporting device therefor comprising a cushion of flexible and elastic material having a frusto-conical outer face provided with approximately uniformly distributed flutes.

11. The combination, with a cup having a frusto-conical forward portion and adapted to be subjected to centrifugal force and a glass tube insertable in the cup, of a flexible and elastic cushion, adapted to prevent breakage of the tube while it is subjected to centrifugal force, the interior of which is fittable upon and around the forward end of the tube and which has a frusto-conical exterior provided with substantially uniformly distributed projecting members deformable by contact with the enclosing cup and thereby providing uniform support for the glass tube.

ALAN E. FLOWERS. 

